Attenuation of Postmeal Metabolic Indices with Red Raspberries in Individuals at Risk for Diabetes: A Randomized Controlled Trial

Abstract

Objective This study investigated the effect of red raspberry intake on meal‐induced postprandial metabolic responses in individuals who have overweight or obesity with prediabetes and insulin resistance (PreDM‐IR), and in metabolically healthy individuals (Reference). Methods Thirty‐two adults (PreDM‐IR, n = 21; Reference, n = 11) were randomized to a controlled, three‐arm, single‐blinded, crossover trial. Participants were provided 0 g of frozen red raspberries (Control), 125 g of frozen red raspberries (RR‐125) (~1 cup), or 250 g of frozen red raspberries (RR‐250) (~2 cups), with a challenge breakfast meal (high carbohydrate/moderate fat) on three separate days. Multiple blood samples were collected up to 8 hours post breakfast with a final blood sample at 24 hours. A snack was provided at 6 hours. Results Breakfast containing RR‐125 and RR‐250 significantly reduced 2‐hour insulin area under the curve, and RR‐250 reduced peak insulin, peak glucose, and 2‐hour glucose AUC compared with Control in the PreDM‐IR group (P < 0.05). Postprandial triglycerides were significantly lower after RR‐125 versus RR‐250 (P = 0.01) but not different from Control (P > 0.05). No significant meal‐related differences were observed for oxidative stress or inflammatory biomarkers. Conclusions Our findings suggest that red raspberries aid in postmeal glycemic control in individuals with PreDM‐IR, reducing glycemic burden with less insulin, which may be related to improved tissue insulin sensitivity.

Plasma and Urinary (Poly)phenolic Profiles after 4-Week Red Raspberry (Rubus idaeus L.) Intake with or without Fructo-Oligosaccharide Supplementation

“…A limitation was the variance in RRB used in the test drink and those used for the 4-week supplementation. However, this is also valuable because the bolus amount of RRB (poly)phenols and single-cultivar RRB in the RRBtest drink enables the comparison with our previous acute study [ 31 ], and the RRB in the 4-week supplementation is consistent with typical intake of multiple RRB varieties in marketplace. Additionally, the amount (1 cup/d) was practical for participants to consume daily.…”

“…Subjects were required to meet general eligibility criteria and specific criteria for PreDM-IR. Specific PreDM-IR criteria included impaired fasting glucose (≥5.6 mmol/L and <7.0 mmol/L), elevated fasting insulin (>50th percentile cutoff) [ 32 ], and insulin resistance measured by homeostatic model assessment of insulin resistance, HOMA-IR ≥ 2 [ 31 ]. The Reference/Control group had fasting glucose values ≤ 5.6 mmol/L and a HOMA-IR value ≤ 1 [ 31 ].…”

“…Specific PreDM-IR criteria included impaired fasting glucose (≥5.6 mmol/L and <7.0 mmol/L), elevated fasting insulin (>50th percentile cutoff) [ 32 ], and insulin resistance measured by homeostatic model assessment of insulin resistance, HOMA-IR ≥ 2 [ 31 ]. The Reference/Control group had fasting glucose values ≤ 5.6 mmol/L and a HOMA-IR value ≤ 1 [ 31 ]. General eligibility criteria for individuals to participate in the study were: non-smoker and not taking any medications that would interfere with outcomes of the study (i.e., lipid-lowering, anti-inflammatory, or glucose-interfering medications or dietary supplements), no known allergy or intolerance to berries, did not consume ≥3 servings of berries per week, and had no documented atherosclerotic disease, inflammatory disease, –GI or kidney disease, diabetes mellitus, or other systemic diseases.…”

“…Wakefield, Enfield Farms, Lynden, WA, USA) and 65 g dextrose ( Table 1 and Supplementary Table S1 ). The 250 g RRBtest drink was chosen based on our prior research [ 31 ] and aims to deliver a bolus amount of red raspberry (poly)phenols to characterize (poly)phenolic metabolites over a 24 h period in plasma and urine. Subjects were asked to consume fixed meals provided by the CNRC the night before and on each PKD.…”

Characterization of the nutrient profile of processed red raspberries for use in nutrition labeling and promoting healthy food choices

“…Processed red raspberries have been studied for their health benefits in models of age-related chronic diseases. The consumption of frozen red raspberries compared to a control lowered postprandial hyperglycemia and inflammation in adults with prediabetes or diabetes [35,36]. Red raspberry juice intake improved the lipids profile, antioxidant status and reduced the risk of developing atherosclerosis in hamsters consuming an atherogenic diet [37].…”